Yellowstone National Park wolf project leader Dr. Doug Smith checks the new radio collar on a tranquilized wolf during collaring operations in Yellowstone on 1-09-03. Higher resolution of this image not available.

Wood bison are the largest native land mammals in the Western Hemisphere, 10 to 15% heavier than plains bison. Bulls are slightly larger than cows and average around 1,800 pounds, but can get up to 2,000 pounds. Both males and females have short...

William Souder’s work has appeared in many publications, including the Washington Post, New York Times, and Harper’s. He is the author of three books. A Plague of Frogs (2000) followed the investigation into outbreaks of deformed frogs across...